What’s behind Florida’s algae bloom? Satellite photos reveal clues.

A toxic algae bloom, so large it is visible from space, has been expanding in Florida’s Lake Okeechobee since May and has spread through the St. Lucie River estuary to the Atlantic Ocean. The algae invasion has made the water unfit for consumption and agriculture and prompted Governor Rick Scott to declare a state of emergency in two south Florida counties, as scientists and politicians dispute just what’s to blame.

Satellite photos taken on July 2 by NASA’s Operational Land Imager reveal an expanding patch of single-celled organisms called cyanobacteria (colloquially known as blue-green algae, although it is really a bacteria). The bloom covers approximately 33 square miles of the Lake Okeechobee, which at 720 square miles is the second largest lake completely within the United States, after Lake Michigan.

“Human activities have dramatically increased nitrogen and phosphorus inputs into many rivers and lakes, causing algal blooms that threaten economic and recreational uses of those waters,” Hans Paerl, professor of marine and environmental sciences at the University of North Carolina-Chapel Hill Institute of Marine Sciences, told LiveScience. READ MORE.